Self-obturating gas-operated launcher

ABSTRACT

A SELF-OBTURATING, GAS-OPERATED LAUNCHER PARTICULARLY SUITED FOR USE IN LAUNCHING PROJECTILES IN A DECONTAMINATED MEDIUM, CHARACTERIZED BY THE UTILIZATION OF AN ELONGATED BARREL INCLUDING A RIGID, BARREL-SEALING BREECH BLOCK, A MUZZLE BLOCK HAVING A BORE THROUGH WHICH A PROJECTILE IS EJECTED AND A MALLEABLE SLUG DISPOSED WITHIN THE BARREL ADJACENT TO THE BREECH BLOCK DEFINING AN EXPANDABLE FIRING CHAMBER WITHIN THE BARREL AND ADAPTED TO THE DRIVEN TOWARD THE MUZZLE BLOCK FOR LAUNCHING A PROJECTILE AS A PYROTECHNIC MATERIAL IS IGNITED WITHIN THE CHAMBER, A FEATURE OF THE LAUNCHER BEING A PLURALITY OF OPENINGS FORMED WITHIN THE MUZZLE BLOCK FOR RELIEVING BACK-PRESSURE, AND AN ANNULAR ANVIL CIRCUMSCRIBING THE BORE OF THE MUZZLE BLOCK FOR RECEIVING THE MALLEABLE SLUG IN IMPACTED ENGAGEMENT FOR THUS ACHIEVING AN HERMETIC SEALING OF THE BORE THEREBY TO RETAIN WITHIN THE BARREL THE RESIDUE OF THE IGNITED PYROTECHNIC MATERIAL.

Nov. 16, 1 3,619,924

A NISTRATOR o TIONAL AERONAUTICS AND SPACE ADMINISTRATION SELF-OBTURATING, GAS-OPERATED LAUNCHER Filed Sept. 17 1969 A TTORNEVS United States Patent O 3,619,924 SELF-OBTURATING, GAS-OPERATED LAUNCHER T. 0. Paine, Administrator of the National Aeronautics and Space Administration, with respect to an invention of Otto K. Heiney, Temple City, Calif.

Filed Sept. 17, 1969, Ser. No. 853,695 lint. Cl. F41c 11/00; F41f 17/00; F42b 11/42 US. Cl. 421 1F 1 Claim ABSTRACT OF THE DISCLOSURE A self-obturating, gas-operated launcher particularly suited for use in launching projectiles in a decontaminated medium, characterized by the utilization of an elongated barrel including a rigid, barrel-sealing breech block, a muzzle block having a bore through which a projectile is ejected and a malleable slug disposed within the barrel adjacent to the breech block defining an expandable firing chamber within the barrel and adapted to be driven toward the muzzle block for launching a projectile as a pyrotechnic material is ignited within the chamber, a feature of the launcher being a plurality of openings formed within the muzzle block for relieving back-pressure, and an annular anvil circumscribing the bore of the muzzle block for receiving the malleable slug in impacted engagement for thus achieving an hermetic sealing of the bore thereby to retain within the barrel the residue of the ignited pyrotechnic material.

ORIGIN OF INVENTION The invention described herein was made in the performance of work under a NASA contract and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 85-568 (72 Stat. 435; 42 USC 2457).

BACKGROUND OF THE INVENTION (1) Field of the invention The invention relates to gas-operated launchers and more particularly to a self-obturating, gas-operated launcher adapted to employ ignited pyrotechnic materials for launching projectiles into an ambient medium while precluding a discharge of products of expended pyrotechnic materials.

(2) Description of the prior art The prior art is replete with projectile launching devices which employ pyrotechnic materials of the types commonly referred to as explosives and propellants. Normally such materials, upon being fired within a firing chamber, generate rapidly expanding gases which act against projectiles for imparting acceleration thereto. Among such devices are rifles, mortars, and guns of the general variety, including spear guns and launchers for similar elongated projectiles.

Among the heretofore unsolved problems inherent in launching projectiles, through a use of expanded gases derived from ignited or detonated pyrotechnic materials, is the introduction of the resultant residue into the ambient medium which, for purposes of explanation, includes gas, water and vacuum.

Normally, the expanded gases and consumed pyrotechnic material are discharged from a launcher as the projectile exits its muzzle. In so doing, the heated gases introduce numerous side efiects, some of which frequently are found to be particularly undesirable. For example, where a projectile is launched in the vicinity of a celestial body, gases and other products of the ignited pyrotechnic material tend to contaminate the ambient medium. Also,

3,619,924 Patented Nov. 16, I971 ice OBJECTS AND SUMMARY OF THE INVENTION This invention overcomes many of the aforementioned difficulties through the use of a simplified obturating muzzle block and a displaceable, malleable slug adapted to launch projectiles from an elongated barrel and to establish an hermetically sealed muzzle, which is efiective in obviating a discharge of products of expended pyrotechnic materials.

Accordingly, an object of the instant invention is to provide a self-obturating, gas-operated launcher.

Another object is to provide a self-obturating launcher particularly adapted for use in launching projectiles through the use of ignited pyrotechnic materials.

Another object is to provide a self-obturating launcher for use in launching projectiles, through an ignition of pyrotechnic materials, into an ambient medium while retaining all residue of the ignited pyrotechnic materials within the launcher.

Another object is to provide a self-obturating launcher adapted to employ expanded gases of ignited pyrotechnic materials for ejecting a spin-stabilized projectile from the launcher and delivering it along a preselected path without subjecting the ambient medium to effects of ignited pyrotechnic materials.

These together with other objects and advantages will become more readily apparent by reference to the following description and claim in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sectioned elevation of a self-obturating gasoperated launcher employing the principles of the present invention, illustrating a projectile arranged in a pre-launch configuration within the barrel of the launcher.

FIG. 2 is a sectioned, fragmented view of the launcher, on somewhat of an enlarged scale, illustrating the launcher in an actuated configuration.

FIG. 3 is 'a cross section view taken generally along line 3-3 of FIG. 1.

FIG. 4 is a side elevation of a projectile having a spinstabilizing fin for imparting to the projectile spin-stabilization characteristics.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. 1, a self-obturating launcher 10 embodying the principles of the present invention is illustrated in a pre-launch configuration having seated therein a projectile 12. The launcher includes an elongated tubular body 14 having a breech 15 and including therein an internal bore 16 of a cylindrical configuration extending from the breech 15 to a muzzle 17. The breech 15 is closed through a removable breech block 18. As presently employed, the breech block is a closure cap sealingly secured to one end of the barrel through mated opposed screw-threads 20 and 21 suitably provided at the contiguous surfaces of the body and cap, respectively.

The breech block 18 includes therein an initiator cavity 22 into which is seated an initiator 24. The initiator is formed as a charge of a suitable pyrotechnic material which is ignited for purposes of igniting a larger charge of pyrotechnic materials. As currently employed, the initiator 24 is a squib having embedded therein a suitable resistant bridge wire, not shown, operatively connected with a pair of electrical leads 26. The leads 26 are ex- 3 tended through a suitably sealed opening 27 formed in the breech block and are electrically connected with a suitable source of electrical potential, also not shown. Of course, it should readily be apparent that, where preferred, the initiator 24 may be replaced by a percussion cap of any suitable design. In such instances versatility is imparted to the launcher, since the launcher thus equipped can be employed in the absence of a source of electrical potential.

Adjacent to the initiator 24, within the bore 16 of the body 14, there is provided a firing chamber 28. The firing chamber 28 serves to receive a pyrotechnic material 30 of a suitable composition selected on a basis of compatibility with the purpose of the launch. While, in practice, the pyrotechnic material is formed of a readily available propellant an explosive material may be employed, depending upon the nature and function of the projectile 12 and the environment into which the projectile is to be launched. In any event, the pyrotechnic material 30 is of the type which will respond to actuation of the initiator 24 for generating rapidly expanding gases within the firing chamber.

Defining the forwardmost end of the firing chamber 28, there is a displaceable slug 32. The slug 32 is of a cylindrical configuration having an outside diameter approximating the inside diameter of the bore 16 in order that the slug be received within the bore and an hermetic seal be established between the surfaces thereof. As a practical matter, the slug 32 is formed of a malleable material, such as lead, for example, and is adapted to be forwardly displaced in response to an expansion of gases generated within the firing chamber 28 as a pyrotechnic material is actuated therein.

The leading end portion of the slug 32 is provided with a concentrically arranged recess which defines a socket 34 into which the rearmost end of the elongated projectile 12 is inserted and mated preparatory to its launching. While various means, including lock rings. springs, spring-loaded detents and the like, may be employed for retaining an end of an associated projectile within the socket 34, as a practical matter, forces of friction have served quite satisfactorily for this purpose.

At the muzzle 17 of the tubular body 14 there is provided a muzzle block 36 disposed in a coaxial relationship with the slug 32. The muzzle block includes an axial bore 37 having a diameter less than the external diameter of the projectile 12. However, along the internal surfaces of the bore 37 there is provided a plurality of slotted openings or grooves 38 arranged in a parallel disposition and establishing therebetween a multiplicity of projectile supporting surfaces or lands 40. The purpose of the lands is to engage the external surfaces of the projectile 12 so long as it is received Within the bore 37, while the grooves accommodate a discharge of fluids from the bore 16 through the muzzle block.

Due to the presence of the grooves 38, entrapment of pressure within the bore 16, as the slug 32 is advanced, is inhibited since the grooves 38 permit the bore 16 to communicate with the ambient medium into which the projectile 12 is being launched. Hence, as the slug is advanced, the pressure which otherwise would develop along the slugs leading surfaces remains negligible as the medium within the bore is discharged through the grooves. While lands and grooves have proven quite satisfactory for use in avoiding pressure build-up, it should be appreciated that tubular openings extending through the muzzle "block can also be employed.

The muzzle block 36 further is provided with an annular shoulder 42 of a truncated, frusto-conical configuration. The shoulder 42 includes an inclined face 44 which extends inwardly toward the slug 32 and terminates at the bore 37. The face 44 serves as an imparting surface for the slug 32 as its advancement is arrested, subsequent to its being propelled forwardly.

As best shown in FIG. 2. the slug 32 also is provided with an annular shoulder 46 conforming to a frustoconical configuration. This shoulder includes a face 48 extending from the external surface of the slug and terminating at the socket 34 in a manner such that it forms a mirror image of the face 44 upon which it is adapted to seat.

It is particularly important to note that the grooves 38 are of insuflicient depth to extend to the surface of the bore 16. Consequently, the peripheral portion of the face 48 of the shoulder 46 is mated with a peripheral portion of the face 44 between the grooves and the surface of the bore 16. Therefore, it should be appreciated that as the slug 32 is impacted against the muzzle block 36, the face 48 of the annular shoulder 46 of the slug 32 is mated with the face 44 of the shoulder 42 formed on the muzzle block 36. Since the slug 32 is formed of a malleable material, the shoulders 42 and 46 become tightly mated whereby an hermetic seal is established at the interfaces to preclude a discharge of the residue of the consumed pyrotechnic material.

The muzzle block 36 may be coupled with an end portion of the body 14 of the launcher 10 through various suitable devices, including an annular coupling collar 50. The collar 50 is provided with a radially extended annulus 52 having a radial locking face 53 directed inwardly from the periphery of the collar. The face of the annulus is mated with an outwardly extended shoulder 54 formed about the periphery of the muzzle block 36. In order to couple the collar 50 with the body 14 of the launcher 10, the collar is provided with an internally screw-threaded surface 56 while the adjacent end portion of the body 14 is provided with an externally screwthreaded surface 58. Therefore, simply by advancing the threaded surface of the collar along the threaded surface of the body 14 of the launcher 10, the muzzle block 36 is brought into a sealed relationship with the muzzle of the launcher.

As illustrated in FIG. 1, the launcher 10 is disposed in a mount 60 supported by suitable base structure 62. The base serves to position the launcher 10 in a desired attitude relative to a selected target. However, the manner in which the launcher is mounted is a matter of convenience only and therefore the mount 60 may be varied as desired, depending upon its use in a given operative environment.

Frequently, the target selected requires an accurate delivery of the projectile 12. In such instances it may be desirable to provide the projectile with spin-stabilization characteristics. To achieve such characteristics, the projectile 12 is provided with a helical fin 64 adapted to seat within one of the grooves 38 as the projectile is prepared for launch. Consequently, as the projectile is ejected from the bore 16, the surfaces of the associated groove acting on the helical fin serve to impart a rate of rotation to the projectile whereupon spin-stabilization of the projectile is realized.

OPERATION It is believed that in view of the foregoing description, the operation of the device will be readily understood, however, it will be briefly reviewed at this point. With the launcher 10 disassembled, that is, with the breech block 18 removed from the body 14 of the launcher 10, a slug 32 is inserted into the bore 16 and advanced a selected distance along the bore 16 for defining a firing chamber 28. Into this chamber there is inserted a charge of pyrotechnic material 30 of a selected composition, normally, a propellant. However, the material may be an explosive charge, if such is preferred. In any event, an initiator 24 is inserted into a cavity 22 with its leads 26 being extended through the opening 27, which is then sealed in any convenient manner, including the use of a selected epoxy cement. The breech block 18 is mounted and coupled with the body 14, through a mating of the screw-threads 20 and 21, for thereby closing the breech 15. As a practical matter, preparatory to each launching of a projectile 12, a new muzzle block 36 is coupled with the muzzle of the launcher 10.

With the device thus assembled, a stem of an elongated projectile 12 is inserted through the bore 37 of the muzzle block 36 and seated within the socket 34 of the slug 32. The leads 26 now are electrically coupled with a source of electrical potential preparatory to a launching of the projectile 12. Should it be preferred to do so, a precussion cap may be seated in the cavity 22 with an appropriate portion thereof being in communication with the opening 27 in order that the device may be fired mechanical without dependence upon a source of electrical potential.

At an appropriate instant, an electrical signal is delivered through the leads 26 for firing the initiator 24, whereupon heated gases are delivered to the pyrotechnic material 30 for igniting this material. As the material 30 is burned, additional hot gases are generated and caused rapidly to expand within the chamber 28 of the bore 16. As the gases are expanded, the slug 32 is advanced toward the muzzle 17 at an accelerating rate. The projectile 12 also is accelerated in response to the slugs displacement and ultimately is launched from the bore 16. As the slug 32 approaches the muzzle block 36, the faces 48 and 44 are brought into an impacting engagement, whereupon the shoulder 46', at the interface, is deformed to assure formation of an hermetic seal at the interface of the slug and muzzle block for thereby sealing the bore 37 and grooves 38. As the resulting seal serves to confine the residue of combustion of the pyrotechnic material, including gases, ashes and the like Within the bore 16, the ambient medium remains free from contamination. Of course, it should readily be appreciated that since the bore is sealed, shock waves established at the firing of the pyrotechnic material are retained within the bore 1 6 of the launcher so that only a minor report or no explosive report issues from the launcher as the projectile is driven toward its target.

It is also quite important to note that due to the presence of the grooves 38 back-pressure is maintained at a negligible level within the bore 16 as the slug 32 is advanced, since the grooves 38 of the muzzle portion of the bore 16 are in direct communication with the ambient medium so that as the slug is advanced any medium present at the leading portion of the slug is ejected through the grooves, prior to their being sealed by the shoulder 46.

In view of the foregoing it should readily be apparent that the instant invention is embodied in a launcher wherein a pyrotechnic material is ignited for effecting a launching of a projectile, while all by-products of the ignition, including heated gases, burned material, and resulting shock waves are retained within its bore.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention.

What is claimed is:

6 1. A self-obturating, gas-operated launcher for launching a projectile having an elongated body of a cylindrical configuration comprising:

(A) an elongated body having in coaxial relationship a breech, a muzzle, and a tubular bore axially extending therebetween;

(B) a breech block closing said breech and having a squib-receiving cavity formed therein;

(C) means defining an opening extending from said cavity through said breech block providing an electrical conduit between the cavity and the external surface of the breech block;

(D) a cylindrical slug formed of a malleable material seated within said tubular bore in spaced relationship with said breech block defining a firing chamber adjacent to said breech block and including a projectile-receiving socket concentrically related to said bore for receiving an end of the projectile preparatory to firing a pyrotechnic material within the chamber;

(E) a muzzle block coaxially related to said breech block coupled with said muzzle including means defining therein -a cylindrical bore having a diameter substantially equal to the diameter of the body of the projectile and coaxial'ly related to said socket and means defining about said bore a plurality of pressure-relief openings communicating with said tubular bore;

(F) means defining a slug-impacting shoulder of a frusto-conical configuration extending axially from the internal surfaces of said muzzle block in a manner such as to intercept and arrest advancement of the displaceable slug as it is advanced by a firing of a pyrotechnic material within said firing chamber; and

(G) means defining in said slug a shoulder surface of an outwardly flared, frusto-conical configuration of a dimension substantially equal to the dimension of the slug-impacting shoulder circumscribing said projectile-receiving socket for hermetically sealing said pressure-relief openings as advancement of the slug is arrested, whereby an hermetic seal is established at the muzzle block for obviating a discharge of by-products of combustion as a projectile is ejected from the launcher.

References Cited UNITED STATES PATENTS 2,499,379 3/1950 Garrett 42-1 F 2,993,291 7/1961 Rouby 42-84 3,151,412 10/1964 Swindle 42-78 X 3,404,599 10/ 1968 Annis 89-1 3,416,402 12/1968 Griessen 42-1 F X BENJAMIN A. BORCI-IELT, Primary Examiner I. M. HANLEY, Assistant Examiner U.1S. Cl. X.R. 

